1) Field of the Invention
The present invention relates to the field of mechanical horology. It concerns, more particular, a mechanism known by one skilled in the art under the name of minute repeater.
2) Description of Related Art
A device of this type makes it possible to indicate, upon request, the time to the closest minute, using blows struck by two hammers on two different gongs. The hammers are actuated by pallets which are lifted by a striking mechanism. This mechanism comprises an hour part, quarter part and minute part, equipped with twelve, three and fourteen teeth respectively to strike the hours, quarters and minutes.
In order to control the movement of these pieces, an hour snail is disposed on a star having twelve teeth, advancing by one step each hour, while a quarter snail and minute snail are adjusted on the rod of the cannon-pinion. Three levers, each provided with a sensing arm cooperating with these snails, make it possible to determine the travel of the hour, quarter and minute parts and to adjust the number of blows struck.
One will find other details on this type of complication, in particular on the driving force of the repeater or on the trigger step, meaning on triggering of the striking mechanism, in the book “Théorie de l'horlogerie” by Reymondin et al, Fédération des Ecoles Techniques, 1998, ISBN 2-940025-10-X, pages 219 to 224.
One of the many complexities of this mechanism comes from the large number of parts which must be coordinated and adjusted so as to achieve proper operation.